Adds GeolocationFeature for Blimp Geolocation project.

blimp/client/feature/geolocation_feature.cc

Index: blimp/client/feature/geolocation_feature.cc
diff --git a/blimp/client/feature/geolocation_feature.cc b/blimp/client/feature/geolocation_feature.cc
new file mode 100644
index 0000000000000000000000000000000000000000..641b95999066dac097eb0f4ce48d22d9c440bc90
--- /dev/null
+++ b/blimp/client/feature/geolocation_feature.cc
@@ -0,0 +1,137 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "blimp/client/feature/geolocation_feature.h"
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include "blimp/common/create_blimp_message.h"
+#include "blimp/common/proto/blimp_message.pb.h"
+#include "device/geolocation/geoposition.h"
+#include "device/geolocation/location_provider.h"
+#include "net/base/net_errors.h"
+
+namespace blimp {
+namespace client {
+
+GeolocationFeature::GeolocationFeature(
+    std::unique_ptr<device::LocationProvider> location_provider) {
+  DCHECK(location_provider);

[Wez, 2016/08/02 01:18:10]

nit: Strictly you don't need this, since you de-reference location_provider_
below.

[CJ, 2016/08/03 20:06:03]

Done.

+  location_provider_ = std::move(location_provider);

[Wez, 2016/08/02 01:18:10]

nit: Move this std::move() to be a member-initialization.

[CJ, 2016/08/03 20:06:03]

Done.

+  location_provider_->SetUpdateCallback(base::Bind(
+      &GeolocationFeature::OnLocationUpdate,
+      base::Unretained(this)));
+}
+
+GeolocationFeature::~GeolocationFeature() {}
+
+void GeolocationFeature::set_outgoing_message_processor(
+    std::unique_ptr<BlimpMessageProcessor> processor) {
+  outgoing_message_processor_ = std::move(processor);
+}
+
+void GeolocationFeature::ProcessMessage(
+    std::unique_ptr<BlimpMessage> message,
+    const net::CompletionCallback& callback) {
+  DCHECK_EQ(BlimpMessage::kGeolocation, message->feature_case());
+
+  const GeolocationMessage& geolocation_message = message->geolocation();
+  switch (geolocation_message.type_case()) {
+    case GeolocationMessage::kSetInterestLevel: {
+      const GeolocationSetInterestLevelMessage& set_level_message =
+          geolocation_message.set_interest_level();
+      OnGeolocationInterestUpdate(set_level_message.level());
+      break;
+    }
+    case GeolocationMessage::kRequestRefresh:
+      location_provider_->RequestRefresh();
+      break;
+    case GeolocationMessage::kCoordinates:
+    case GeolocationMessage::kError:
+    case GeolocationMessage::TYPE_NOT_SET:
+      DLOG(FATAL) << "Unsupported message type.";

[Wez, 2016/08/02 01:18:10]

nit: This should be "Invalid message type." - "Unsupported" implies that we just
haven't implemented it yet!  However, I'd personally suggest omitting the
message entirely, since only Debug builds will fire this, and the developer can
see what triggered the failure from the stack + code easily enough.

[CJ, 2016/08/03 20:06:03]

Done.

+      callback.Run(net::ERR_UNEXPECTED);
+      return;
+  }
+  callback.Run(net::OK);

[Wez, 2016/08/02 01:18:11]

nit: Consider using ScopedTaskRunner for this.

As with the EngineGeolocationFeature, remember that it is valid to supply
ProcessMessage() with a null |callback| - ScopedTaskRunner will implicitly deal
with that case for you, or you can explicitly add an is_null() check before the
Run(), if you want.

[CJ, 2016/08/03 20:06:03]

Done.

+}
+
+void GeolocationFeature::OnLocationUpdate(
+    const device::LocationProvider* location_provider,
+    const device::Geoposition& position) {
+  if (position.error_code == device::Geoposition::ERROR_CODE_NONE) {
+    SendGeolocationPositionMessage(position);
+  } else {
+    SendGeolocationErrorMessage(position.error_code, position.error_message);

[Wez, 2016/08/02 01:18:10]

If you change the signature of SendGeolocationErrorMessage() to take a
GeolocationErrorMessage::ErrorCode as parameter then you can have this method
use a switch, and get rid of the NOTREACHED() case in
SendGeolocationErrorMessage.  

Downside is that you'll have three cases all calling
SendGeolocationErrorMessage(...) in here, but then you'll only have one
set_error_code() call inside that method, so overall the same # of lines, I
think.

[CJ, 2016/08/03 20:06:03]

Done.

+  }
+}
+
+void GeolocationFeature::OnGeolocationInterestUpdate(
+    GeolocationSetInterestLevelMessage::Level level) {
+  switch (level) {
+    case GeolocationSetInterestLevelMessage::HIGH_ACCURACY:
+      location_provider_->StartProvider(true);
+      break;
+    case GeolocationSetInterestLevelMessage::LOW_ACCURACY:
+      location_provider_->StartProvider(false);
+      break;
+    case GeolocationSetInterestLevelMessage::NO_INTEREST:
+      location_provider_->StopProvider();
+      break;
+  }
+}
+
+void GeolocationFeature::SendGeolocationPositionMessage(
+    const device::Geoposition& position) {
+  GeolocationMessage* geolocation_message = nullptr;
+  std::unique_ptr<BlimpMessage> blimp_message =
+      CreateBlimpMessage(&geolocation_message);
+  GeolocationCoordinatesMessage* coordinates =
+      geolocation_message->mutable_coordinates();
+
+  coordinates->set_latitude(position.latitude);
+  coordinates->set_longitude(position.longitude);
+  coordinates->set_altitude(position.altitude);
+  coordinates->set_accuracy(position.accuracy);
+  coordinates->set_altitude_accuracy(position.altitude_accuracy);
+  coordinates->set_heading(position.heading);
+  coordinates->set_speed(position.speed);
+
+  outgoing_message_processor_->ProcessMessage(std::move(blimp_message),
+                                              net::CompletionCallback());

[Wez, 2016/08/02 01:18:10]

nit: Perhaps we should register a completion callback and only send a new
position update if the network is ready for it?

[CJ, 2016/08/03 20:06:03]

How does one know if the network is ready?

[Wez, 2016/08/09 01:40:33]

By passing a non-null CompletionCallback and setting a Boolean in the
GelocationFeature - then when the callback fires you clear the Boolean. While
the Bool is set you never send out any further updates.  That way if the
outgoing MessageProcessor is slow, you won't flood it with data. :)

[CJ, 2016/08/09 21:40:37]

Done.

+}
+
+void GeolocationFeature::SendGeolocationErrorMessage(
+    const device::Geoposition::ErrorCode& error_code,
+    const std::string& error_message) {
+  GeolocationMessage* geolocation_message = nullptr;
+  std::unique_ptr<BlimpMessage> blimp_message =
+      CreateBlimpMessage(&geolocation_message);
+
+  GeolocationErrorMessage* error = geolocation_message->mutable_error();
+  switch (error_code) {
+    case device::Geoposition::ErrorCode::ERROR_CODE_PERMISSION_DENIED:
+      error->set_error_code(GeolocationErrorMessage::PERMISSION_DENIED);
+      break;
+    case device::Geoposition::ErrorCode::ERROR_CODE_POSITION_UNAVAILABLE:
+      error->set_error_code(GeolocationErrorMessage::POSITION_UNAVAILABLE);
+      break;
+    case device::Geoposition::ErrorCode::ERROR_CODE_TIMEOUT:
+      error->set_error_code(GeolocationErrorMessage::TIMEOUT);
+      break;
+    case device::Geoposition::ErrorCode::ERROR_CODE_NONE:
+      NOTREACHED();
+      break;
+  }
+
+  error->set_error_message(error_message);
+
+  outgoing_message_processor_->ProcessMessage(std::move(blimp_message),
+                                              net::CompletionCallback());
+}
+
+}  // namespace client
+}  // namespace blimp